Field of the Invention
The present invention relates generally to acoustic hailing systems.
Related Art
Drivers that convert an electrical signal into acoustical energy or sound waves in order to radiate the sound waves into air have been used for some time. Such devices include direct radiators, which directly radiate the generated sound waves, and indirect radiators, which utilize additional elements for radiating the generated sound waves. In a direct radiator, a diaphragm directly vibrates or moves the surrounding air and generates the sound waves related to the electrical signal. In an indirect radiator, the diaphragm moves against a surface closely spaced thereto and generates high pressure compression waves which are passed through a throat and to a horn or other acoustic generator having a smaller upstream area than the diaphragm. Generally, indirect radiators, such as compression drivers, can generate much higher audible levels when compared with direct radiators and are used, for example, in public address systems.